The former light heavyweight champion admitted to the violation
during an out-of-competition sample collection by the U.S.
Anti-Doping Agency (USADA) last week, according to a statement
released by the UFC on Friday. The substance Machida admitted to
using is currently unknown.

“Machida stated that he was unaware that the substance was
prohibited both in and out of competition and, in accordance with
the UFC Anti-Doping Policy, his disclosure of usage will be taken
into consideration by USADA during any potential results management
and adjudication process,” the statement read.

As a result, a featherweight clash between Cub Swanson
and Hacran Dias
has been moved to the Fox-televised main card. Henderson will be
scheduled for a new bout in the “near future,” according to the
statement.

Machida has lost three of his last four Octagon appearances,
including a third-round technical knockout defeat to Yoel Romero
at UFC Fight Night in Hollywood, Fla., this past June. He
previously defeated Dan
Henderson via split decision at UFC 157 in February 2013.

UFC on Fox 19 takes place at Amalie Arena in Tampa, Fla., and is
headlined by a light heavyweight bout between Glover
Teixeira and Rashad
Evans. The evening’s main card airs on Fox beginning at 8 p.m.
ET/5 p.m. PT.